/**
 * @author wcj
 * @Date 2021/6/7 12:07
 * @Version 1.0
 */
public class DoubleCheck {

    private static DoubleCheck instance;

    public static DoubleCheck getInstance() {
        if (instance == null) {
            synchronized (DoubleCheck.class) {
                if (instance == null) {
                    instance = new DoubleCheck();
                }
            }
        }
        return instance;
    }
}
